This invention relates to an improved process of alkylation of at least one isoparaffin with at least one olefin in the presence of an acid catalyst. In particular, it relates to an alkylation process in which at least a portion of the hydrocarbon liquid withdrawn from a settler is flashed to provide indirect cooling for the alkylation process.
Since the temperature at which alkylation of isoparaffin with at least one olefin in the presence of an acid catalyst (such as HF) is inversely proportional to the octane value of the alkylate produced, it is desirable to carry out the alkylation at a minimum attainable temperature. The cooling of the reaction zone can be provided by any suitable means, but it is economically advantageous to utilize the cooling from within the system. One method proposed for cooling of the alkylation zone, disclosed, for example, in U.S. Pat. No. 3,925,501, is by flashing hydrocarbon liquid withdrawn from the settling zone. The flashing provides cooling which reduces the temperature in the reaction zone. The flashed vapor which contains HF therein is transported into a compressor where its pressure is increased to a level sufficient to pass it to a depropanizer. One problem with this process is the cost associated with the use of a compressor. The usually expensive piece of process equipment is made economically unaffordable by the requirement that those parts which come in contact with hydrofluoric acid must be made of materials which are not corroded by vaporized HF. Since materials that are not corroded by acids such as HF are extremely difficult to obtain and their costs are enormous, the compressors made from these are not readily available and must be custom-made. If the material is even slightly corrosive, frequent replacements of parts increase maintenance costs.
The present invention obviates some of the problems encountered in the prior art. Thus, one object of the present invention is to provide an improved alkylation process.
Another object of the invention is to provide an alkylation process which requires a minimum amount of energy.
Still another object of the invention is to provide a process which will reduce the equipment expenses and maintenance expenses.
A still further object of the invention is to provide a process which utilizes commercially available, mass-produced, inexpensive components.
Other objects of the invention will become apparent to those skilled in the art upon studying this disclosure.